Six component inverted telephoto projection lens

ABSTRACT

A six component f/2.4 inverted telephoto projection or camera lens has seven elements, of which the second and third are a doublet. The first five components form a positive group and are widely separated from a thick negative singlet. Four examples are disclosed. The lens has a magnification ratio of 1:75.

OR 397E090} United State: 111 3,773,403

Lechner et al. 1 Nov. 20, 1973 1 SIX COMPONENT INVERTED TELEPHOTO 3,468,600 9/1969 Hugues 350/215 x PROJECTION LENS Primary Examiner-John K. Corbin Attorney-Frank C. Parker et a].

[5 7 ABSTRACT A six component f/2.4 inverted telephoto projection or camera lens has seven elements, of which the second and third are a doublet. The first five components form a positive group and are widely separated from a thick negative singlet. Four examples are disclosed. The lens has a magnification ratio of 1:75.

5 Claims, 1 Drawing Figure SIX COMPONENT INVERTED TELEPHOTO PROJECTION LENS BACKGROUND 1. Field of the Invention The invention is a six-component lens design.

2. Description of the Prior Art:

While no previous design is known which is substantially that of the instant design family, projection or camera lenses having thick negative singlets or doublets widely separated from positive groups and comprising six or seven components were disclosed in the U.S. Pat. Nos. 2,317,790, 2,612,077, 3,030,860 and 3,064,533.

SUMMARY OF THE INVENTION The lens elements are assembled symmetrically about an optical axis from a short conjugate toward a long conjugate. The aperture is f/2.4 and the magnification ratio is 1:75.

The front lens I on the short conjugate side is a negative meniscus concave toward the long conjugate. It is airspaced from a doublet comprising a meniscus, usually negative, lens 11 in surface contact with a biconvex lens III. Lens IV is a biconcave element narrowly airspaced from lens HI. Lenses V and VI are both biconvex and all the lenses l-Vl are grouped relatively closely to constitute a positive group such as is characteristic of inverted telephoto lenses.

A long space, generally 2 k to 3 times the overall focal length, separates the positive group from a relatively thick negative meniscus lens VII concave toward the short conjugate, and which constitutes the negative portion characteristic of this class of lenses.

EXAMPLES Four examples of the lens in question are set forth by their construction data appearing in the table below. All distances are given in ratio to a desired focal length f, taken as unity. The radii, R, taken as negative when centered on the short conjugate side, thicknesses, t, and spaces, 5, are subnumerated in increasing order toward the long conjugate. The glass types are given by their refractive indices, "D, and dispersion values, v, according to the Fraunhofer analysis, and are similarly subnumerated toward the long conjugate.

'01 1.523 1.523 1.523 1.523 -02 1.639 1.639 1.639 1.639 -03 1.639 1.639 1.639 1.639 "D4 1.720 1.720 1.720 1.720 -05 1.639 1.639 1.639 1.639 "D6 1.640 1.640 1.640 1.640 D7 1.673 1.673 1.673 1.673

v, 58.4 58.4 511.4 53.4 v, 55.3 55.3 55.3 55.3 v, 55.3 55.3 55.3 55.3 v, 29.3 29.3 29.3 29.3 v, 55.3 55.3 55.3 55.3 v, 34.4 34.4 34.4 34.4 v-, 32.1 32.1 32.1 32.1

Those skilled in the art will appreciate that minor variations from these values may still be compensated for by various well known alignment and assembly techniques to provide lenses having commercial potential but which may not exhibit the excellent performance levels attributed to the precise designs disclosed. In particular it is thought that the refractive indices may vary as much as 0.002 and the dispersion values by as much as 2.0 without departing unduly from the basic design family.

We claim:

1. An inverse telephoto lens comprising seven elements of which the second and third are in surface contact, said lens being described by construction data comprising radii, R, taken as negative when centered on the short conjugate side, thicknesses, t, and spaces, s, all given as ratios of the overall focal length, f, and further comprising glass types of refractive index, "D, and dispersion values, v, all of said data being subnumerated in increasing order toward the long conjugate, said data being particularized substantially within the ranges set forth below:

1.255! s R, s 1.325! 0.545! s R, 0.587! 1 .035! s R, s 1. 0.704! s R, s 0.706! 0.923! s R, s 0.959! 0.708! s -R. s r 0.757! 1.798! s R, s 1.979! 7.035! s R, s 1926f 0.862! s R, 5 0.886! 6.053! s R s 9.192! 2.445! S R,, i 2.615! 1. 13 1! s -R,, s 1.360! 8.438! s R,, 5 9.782!

0.173! s 1, s 0.175! 0.260! s t, 5 0.262! 0.348! s 1, s 0.350! 0.086! s 1, 5 0.088! 0.392! s 1, 5 0.404! 0.436! s 1. s 0.438! 0.793! s i, 5 1.381!

0.217! s s, 0.234! 0.044! s .i, s 0.046! 0.121! 6, 5 0.123! 0.016! S s, 0.018! 2.411! s s, 2.923!

1 .521 s D1 s 1 .525 1.637 D2 1.641 1.637 s D3 g 1.641 1 .7 18 s D4 s 1 .722 1 .637 s D5 1 .641 1.638 s D6 s 1 .642 1.671 s D7 i 1.675

56.4 s v, s 60.4 53.3 s v, 57.3 53.3 s v, s 57.3 27.3 s v, s 31.3 53.3 s v, s 57.3 32.4 s v. s 36.4 30.1 s v-, s 34.1

2. The lens of claim 1 having construction data substantially as follows:

3. The lens of claim 1 having construction data substantially as follows:

R. R. R, R4 R. R. R.

4. The lensof claim 1 having construction data substantially as follows: 1

1 .3191 R, 0.5881 R, 1.1151 R4 0.7061 -11. 0.9271 -R. 0.7081 R, Y 1.8821

5. The lens of claim 1 having construction data sub- 

1. An inverse telephoto lens comprising seven elements of which the second and third are in surface contact, said lens being described by construction data comprising radii, R, taken as negative when centered on the short conjugate side, thicknesses, t, and spaces, s, all given as ratios of the overall focal length, f, and further comprising glass types of refractive index, nD, and dispersion values, v, all of said data being subnumerated in increasing order toward the long conjugate, said data being particularized substantially within the ranges set forth below: 1.255f < OR = R1 < OR = 1.325f 0.545f < OR = R2 < OR = 0.587f 1.035f < OR = R3 < OR = 1.120f 0.704f < OR = R4 < OR = 0.706f 0.923f < OR = -R5 < OR = 0.959f 0.708f < OR = R6 < OR = 0.757f 1.798f < OR = R7 < OR = 1.979f 7.035f < OR = R8 < OR = 10.926f 0.862f < OR = -R9 < OR = 0.886f 6.053f < OR = R10 < OR = 9.192f 2.445f < OR = -R11 < OR = 2.615f 1.131f < OR = -R12 < OR = 1.360f 8.438f < OR = -R13 < OR = 9.782f 0.173f < OR = t1 < OR = 0.175f 0.260f < OR = t2 < OR = 0.262f 0.348f < OR = t3 < OR = 0.350f 0.086f < OR = t4 < OR = 0.088f 0.392f < OR = t5 < OR = 0.404f 0.436f < OR = t6 < OR = 0.438f 0.793f < OR = t7 < OR = 1.381f 0.217f < OR = s1 < OR = 0.234f 0.044f < OR = s2 < OR = 0.046f 0.121f < OR = s3 < OR = 0.123f 0.016f < OR = s4 < OR = 0.018f 2.411f < OR = s5 < OR = 2.923f 1.521 < OR = nD1 < OR = 1.525 1.637 < OR = nD2 < OR = 1.641 1.637 < OR = nD3 < OR = 1.641 1.718 < OR = nD4 < OR = 1.722 1.637 < OR = nD5 < OR = 1.641 1.638 < OR = nD6 < OR = 1.642 1.671 < OR = nD7 < OR = 1.675 56.4 < OR = v1 < OR = 60.4 53.3 < OR = v2 < OR = 57.3 53.3 < OR = v3 < OR = 57.3 27.3 < OR = v4 < OR = 31.3 53.3 < OR = v5 < OR = 57.3 32.4 < OR = v6 < OR = 36.4 30.1 < OR = v7 < OR = 34.1
 2. The lens of claim 1 having construction data substantially as follows: R1 1.263f R8 10.926f R2 0.545f -R9 0.862f R3 1.120f R10 9.192f R4 0.706f -R11 2.613f -R5 0.956f -R12 1.360f -R6 0.757f -R13 8.438f R7 1.979f t1 0.174f t7 0.793f t2 0.261f s1 0.223f t3 0.349f s2 0.044f t4 0.087f s3 0.122f t5 0.392f s4 0.017f t6 0.437f s5 2.923f nD1 1.523 v1 58.4 nD2 1.639 v2 55.3 nD3 1.639 v3 55.3 nD4 1.720 v4 29.3 nD5 1.639 v5 55.3 nD6 1.640 v6 34.4 nD7 1.673 v7 32.1
 3. The lens of claim 1 having construction data substantially as follows: R1 1.255f R8 10.768f R2 0.556f -R9 0.863f R3 1.089f R10 8.111f R4 0.704f -R11 2.615f -R5 0.959f -R12 1.333f -R6 0.741f -R13 9.782f R7 1.961f t1 0.174f t7 0.999f t2 0.261f s1 0.225f t3 0.349f s2 0.046f t4 0.087f s3 0.122f t5 0.394f s4 0.017f t6 0.437f s5 2.791f nD1 1.523 v1 58.4 nD2 1.639 v2 55.3 nD3 1.639 v3 55.3 nD4 1.720 v4 29.3 nD5 1.639 v5 55.3 nD6 1.640 v6 34.4 nD7 1.673 v7 32.1
 4. The lens of claim 1 having construction data substantially as follows: R1 1.319f R8 7.336f R2 0.588f -R9 0.886f R3 1.115f R10 6.053f R4 0.706f -R11 2.472f -R5 0.927f -R12 1.131f -R6 0.708f -R13 8.975f R7 1.882f t1 0.174f t7 1.350f t2 0.261f s1 0.234f t3 0.349f s2 0.044f t4 0.087f s3 0.122f t5 0.404f s4 0.017f t6 0.437f s5 2.413f nD1 1.523 v1 58.4 nD2 1.639 v2 55.3 nD3 1.639 v3 55.3 nD4 1.720 v4 29.3 nD5 1.639 v5 55.3 nD6 1.640 v6 34.4 nD7 1.673 v7 32.1
 5. The lens of claim 1 having construction data substantially as follows: R1 1.325f R8 7.035f R2 0.562f -R9 0.874f R3 1.035f R10 6.303f R4 0.706f -R11 2.445f -R5 0.923f -R12 1.160f -R6 0.712f -R13 9.168f R7 1.798f t1 0.174f t7 1.381f t2 0.261f s1 0.217f t3 0.349f s2 0.046f t4 0.087f s3 0.122f t5 0.397f s4 0.017f t6 0.437f s5 2.411f nD1 1.523 v1 58.4 nD2 1.639 v2 55.3 nD3 1.639 v3 55.3 nD4 1.720 v4 29.3 nD5 1.639 v5 55.3 nD6 1.640 v6 34.4 nD7 1.673 v7 32.1 